[XR] Ensure that selectend and selectstart events are always paired

Per the spec, a selectend event should always be sent if a selectstart
event has been fired, evenif the gesture is cancelled.  Currently if an
input source was removed but it had sent a selectstart event a selectend
event would never be sent.  This fixes that for both the cases where an
input source is lost, and if the session ends while a controller is
pressed.

Per the HTML interaction spec, since these removals cannot be
guaranteed to have fired as a result of user interaction, the frame
is not notified of UserActivation in this case (and as such the
OnSelectEnd method is not re-used).

Bug: 968291
Change-Id: Ibea99e59ee7a528b7a34db610bfca76c27d495b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1636851Reviewed-by: Bill Orr <billorr@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Commit-Queue: Alexander Cooper <alcooper@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664805}

third_party/blink/renderer/modules/xr/xr_session.cc

@@ -478,7 +478,9 @@ void XRSession::ForceEnd() {
   pending_frame_ = false;
 
   for (unsigned i = 0; i < input_sources_->length(); i++) {
-    (*input_sources_)[i]->SetGamepadConnected(false);
+    auto* input_source = (*input_sources_)[i];
+    UpdateSelectStateOnRemoval(input_source);
+    input_source->SetGamepadConnected(false);
   }
 
   input_sources_ = nullptr;
@@ -794,6 +796,7 @@ void XRSession::OnInputStateChange(
     auto* input_source = (*input_sources_)[i];
     if (input_source->activeFrameId() != frame_id) {
       inactive_sources.push_back(input_source->source_id());
+      UpdateSelectStateOnRemoval(input_source);
       input_source->SetGamepadConnected(false);
       removed.push_back(input_source);
     }
@@ -918,6 +921,25 @@ void XRSession::UpdateSelectState(
   }
 }
 
+void XRSession::UpdateSelectStateOnRemoval(XRInputSource* input_source) {
+  if (!input_source)
+    return;
+
+  if (input_source->primaryInputPressed()) {
+    input_source->setPrimaryInputPressed(false);
+
+    XRInputSourceEvent* event =
+        CreateInputSourceEvent(event_type_names::kSelectend, input_source);
+    DispatchEvent(*event);
+
+    if (event->defaultPrevented())
+      input_source->setSelectionCancelled(true);
+
+    // Ensure the frame cannot be used outside of the event handler.
+    event->frame()->Deactivate();
+  }
+}
+
 XRInputSourceEvent* XRSession::CreateInputSourceEvent(
     const AtomicString& type,
     XRInputSource* input_source) {

third_party/blink/renderer/modules/xr/xr_session.h

@@ -190,6 +190,7 @@ class XRSession final : public EventTargetWithInlineData,
 
   void UpdateSelectState(XRInputSource*,
                          const device::mojom::blink::XRInputSourceStatePtr&);
+  void UpdateSelectStateOnRemoval(XRInputSource*);
   XRInputSourceEvent* CreateInputSourceEvent(const AtomicString&,
                                              XRInputSource*);
 

third_party/blink/web_tests/xr/xrSession_input_events_end.html

@@ -76,9 +76,9 @@ let testFunction = function(session, t, fakeDeviceController) {
   return session.end().then(() => {
     return sessionEndTest("inputsourceschange", ["inputsourceschange", "end"]);
   }).then(() => {
-    return sessionEndTest("selectstart", ["inputsourceschange", "selectstart", "end"]);
+    return sessionEndTest("selectstart", ["inputsourceschange", "selectstart", "selectend", "end"]);
   }).then(() => {
-    return sessionEndTest("select", ["inputsourceschange", "selectstart", "select", "end"]);
+    return sessionEndTest("select", ["inputsourceschange", "selectstart", "select", "selectend", "end"]);
   }).then(() => {
     return sessionEndTest("selectend", ["inputsourceschange", "selectstart", "select", "selectend", "end"]);
   });